Hard floor surface cleaners are widely used to clean the floors of industrial and commercial buildings. They range in size from a small model that is controlled by an operator walking behind the cleaner and can clean a path ranging from 15 inches to 36 inches wide, to a large model that is controlled by an operator riding on the machine and can clean a path as wide as 5 feet. These hard floor surface cleaners include motorized drive wheels, a solution tank to hold cleaning solution and a recovery tank to hold soiled cleaning solution recovered from the floor being scrubbed. The cleaning solution from the solution tank is applied to the hard floor surface adjacent a scrub head. The scrub head generally contains one or more motorized scrubbing brushes attached either in front of, under, or behind the vehicle. These scrubbing brushes typically rotate to provide the desired scrubbing action. The soiled cleaning solution is then recovered using a solution recovery system, which returns the soiled cleaning solution to the recovery tank.
The cleaning solution is typically gravity fed to the scrub head at a rate that varies in response to the volume of cleaning solution contained in the solution tank. As the volume of cleaning solution contained in the solution tank decreases, the rate at which the cleaning solution is fed to the scrub head decreases. For example, a typical hard floor surface cleaner having a 32 inch wide scrubbing swath applies the cleaning solution to the hard floor surface at a rate that varies from between approximately 1.0 gallons per minute (GPM) when the solution tank is full to a rate of 0.5 GPM when the tank contains a low volume of cleaning solution.
One problem with prior art hard floor surface cleaners has been their limited operational runtime. This is primarily due to their limited solution tank volume and the high cleaning solution flow rates. A typical hard floor surface cleaner having a 32 inch cleaning swatch typically has an operational runtime based on solution capacity of approximately 30–40 minutes, for example.
One possible solution to the short run runtime for these cleaners is to increase the size of the solution and recovery tanks. Unfortunately, such an increase in cleaning solution capacity typically necessitates modifications to the frame and other components of the hard floor surface cleaner, which results in additional weight and higher energy requirements for the device. For most applications, these modifications are impractical.
The high volume flow rate of cleaning solution has been generally desired to provide complete wetting of the floor being cleaned. Unfortunately, the lack of control of the volume flow rate of the cleaning solution results in an excessive amount of cleaning solution being distributed to the floor, when, for example, the solution tank is full. The high volume flow rate of the cleaning solution of prior art hard floor surface cleaners also results in extended downtime. The long downtime periods are generally due to the numerous disposals of soiled cleaning solution and refills of cleaning solution that must be performed for a given job. Additionally, where the cleaning process removes harmful or hazardous chemicals, the disposal of the soiled cleaning solution may require special handling and/or additional costs to ensure that it is disposed of properly. As a result, the large volumes of cleaning solution that are used by prior art hard floor surface cleaners reduce the efficiency at which a cleaning job can be performed.
Consequently, prior art hard floor surface cleaners suffer from several deficiencies that lead to inefficient floor cleaning operations. Most of these deficiencies stem from the poor cleaning solution flow rate control and the high volume flow rate of the cleaning solution that is applied to the hard floor surface.